1+ package com .leetcode .strings ;
2+ 3+ import java .util .ArrayList ;
4+ import java .util .Arrays ;
5+ import java .util .List ;
6+ 7+ /**
8+ * Leetcode Problem: https://leetcode.com/problems/find-all-anagrams-in-a-string/
9+ *
10+ * @author rampatra
11+ * @since 2019年04月13日
12+ */
13+ public class AnagramsInString {
14+ 15+ private static List <Integer > findAllAnagramsInTextNaive (String text , String pattern ) {
16+ List <Integer > indexes = new ArrayList <>();
17+ 18+ int textLen = text .length ();
19+ int patternLen = pattern .length ();
20+ 21+ char [] patternChars = pattern .toCharArray ();
22+ Arrays .sort (patternChars ); // takes O(m log m) time
23+ String sortedPattern = String .valueOf (patternChars );
24+ 25+ String subText ;
26+ char [] subTextChars ;
27+ String sortedSubText ;
28+ 29+ for (int i = 0 ; i <= textLen - patternLen ; i ++) { // loops n-m number of times
30+ subText = text .substring (i , i + patternLen );
31+ subTextChars = subText .toCharArray ();
32+ Arrays .sort (subTextChars ); // sorts m number of characters, takes O(m log m)
33+ sortedSubText = String .valueOf (subTextChars );
34+ 35+ if (sortedSubText .equals (sortedPattern )) { // compare m characters takes m time
36+ indexes .add (i );
37+ }
38+ }
39+ return indexes ;
40+ }
41+ 42+ public static void main (String [] args ) {
43+ // basic use cases
44+ System .out .println (findAllAnagramsInTextNaive ("cbaebabacd" , "abc" ));
45+ System .out .println (findAllAnagramsInTextNaive ("abab" , "ab" ));
46+ 47+ // corner cases
48+ System .out .println (findAllAnagramsInTextNaive ("abab" , "" ));
49+ System .out .println (findAllAnagramsInTextNaive ("" , "ab" ));
50+ System .out .println (findAllAnagramsInTextNaive ("" , "" ));
51+ }
52+ }
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